Process of reducing waste sulfite liquor to a powder.



FREDEEIC H. KENNARD, OF NEWTON, MASSACHUSETTS.

PROCESS OF REDUCING WASTE SULFITE LIQUOR TO A POWDER.

No Drawing.

To all whom it may concern Be it known that I, FREDERIC H. KENNARD,

a citizen of the United States, residing at Newton, in the county ofMiddlesex and State of Massachusetts, have invented an Improvement inProcesses of Reducing Waste Sulfite Liquor to :1. Powder, of which.

the following is a specification.

My invent-ionrelates to a process for the reduction to a dry powderycondition of waste liquor from the manufacture of cellulose from wood bythe sulfite process and to the product derived from such process.Various methods have been suggested for concentratin'g waste sulfiteliquor, but direct evaporationhas been found "to decompose the materialunless some method is adopted to prevent this result and other methodssuggested require the addition of chemicals, which change the materialfrom the product I desire to produce and increase the expense of theprocess. I Y

I begin my process With the sulfite Waste liquor in the acid state inwhich it is produced as a result of the sulfite process, although it isnot important to prevent the free sulfurous acid gas from escaping sofar'as it will, the acid which remains in solution being sufiicient. Ithen concentrate the liquidin a vacuum at a moderate heat until it hasbeen concentrated to a highly viscous state. I have found about 30 Baumsatisfactory. Care should be used, in this early part of theevaporation, not to permit the material to become over-heated generallyor locally. I have found that atemperature of about 205 F issatisfactory for the first part of the evaporation, which may be reducedas the material grows thicker acid reaction, by causmg a precipitatewith to 138 F. Any suitable vacuumpanmay be used. When the material hasbeen reduced to this highly viscous state, it will decompose readily ifevaporated under ordinary conditions, but I have found that if it isheated in a very thin'sheet in a vacuum ata low temperature, it may bereduced to dryness without change of composition from that of theoriginal liquor other-than the driving 03 of the water and free gases.

here are many means which could be adopted for carrying out the secondpart of this process. A satisfactory Way is to QLP'. plythe material ina thin sheet to a hollow rotating metal drum heated to about 135 F.

by interior heat. This drum'.. jgwithin a' vacuum chamber. The viscousmaterial Specification of Letters Patent.

Application filed. January 2, 1914. Serial No. 810,099.

Patented May 4, 1915.

should be applied to the lower part of the roll and evened by aspreading device preferably adjusted from outside the chamber. Thestream will adhere to the roll and proceed around it, drying as itturns, and the speed rotation and thickness of sheet'should be soadjusted that the evaporation will be complete before the liquid hasmade a complete turn. The dried material should then be scraped off theroller and allowed to fall to the bottom of the vacuum chamber, forinstance, by a scraper in contact with the roll and the cleaned surfaceof the roller will then be ready for more material. In this way theprocess is continuous, unless the vacuum chamber is opened to withdrawthe product, and I prefer to use means to permit the withdrawal of thematerial withou breaking the vacuum.

While this device is obviously expeditious, the same process mayobviously be carried out in many other ways, so long as the vitalfeature of applying the material in a thin sheet to a heated surface ina vacuum chamber is preserved.

For most purposes the dried material can be more readily used after ithas been reduced to a powder, and this process'will re-. duce it into apowder but if desired it may be further ground to remove all lumps orimprove the texture.

The dried. product is a. Very strong adhesive, satisfactory for manypurposes. have suggested one of these uses, namely; binding cores forcastings, in a co-pending application, but there are many other uses forthis product.

My new product differs from previous products and is characterized byhaving an gelatin solution and by having substantially the same chemicalcomposition as the sulfite waste liquor from which it was produced,except for the absence of the volatile materials.

I have used the term in a vacuum in this specification to mean operationin a chamber from whichthe atmospheric pressure has been removed to asubstantial extent. I prefer to' use a. good commercial vacuum, say 27inches of mercury, but much less may be used without harm to theproduct, although it will slow up the process.

The term dryness in this specification does not mean theabsoluteelimination of ing of the powdered d-ryproduct from the evaporation ofWaste sulfite liquor having an acid reaction, the original composition,being substantially conserved.

In testimony whereof, I have signed my name .to this specification, inthe presence of two subscribing Witnesses.

' FREDERIC H. KENNARD.

Witnesses:

HnoToR M. HOLMIES, GEORGE C. AnvEDsoN.

